The cool dry air in the winter months makes this an especially good area for walking. Despite all my warnings about the UXO/ERW situation, you will be safe if you stay on tracks and in villages.
Given that, walking and cycling would be a fascinating way to see this unknown corner of the world, inhabited by an extremely friendly and fascinating people. While many villages moved away from the area during the early 1970s because of the war, they are keen to show you the old villages and forests.
The plateau is largely flat and most tracks work on a 'herringbone principal" with the main tracks running along the ridges with side paths off to the valleys below. Note that from the air, one particular new forestry track runs (roughly E to W) across the entire plateau then ends suddenly just a few km short of O Rang village. It would NOT be safe to go cross-country here. The area around O Rang is particularly dangerous.